1. Technical Field
The present invention relates to a drive unit for a switching element which is a target to be driven (hereinafter, referred to as “target switching element”). The target switching element is a voltage control type switching element. The drive unit changes the target switching element between an on-state and an off-state, by controlling a potential difference between a reference terminal, which is one of a pair of ends of a current path of the target switching element, and an opening and closing control terminal of the switching element.
2. Related Art
For example, JP-A-2012-34450 discloses a configuration which includes a function of determining whether or not a voltage (gate voltage) between the gate and the emitter of an IGBT (Insulated gate bipolar transistor), which is the target switching element, is an intermediate voltage, which is higher than a threshold voltage by which the IGBT is turned on but is lower than a voltage applied to the gate when the IGBT is turned. According to this configuration, the IGBT can be forcibly turned off, if the gate voltage remains an intermediate voltage even though the IGBT is being turned on or off.
However, the above technique has the following disadvantages. First, when the IGBT is being turned off, in addition to the problem that the gate voltage may remain at the intermediate voltage, it is also a problem that the gate voltage may remain at a voltage higher than the intermediate voltage. Second, when the IGBT is being turned on, in addition to the problem that the gate voltage remains the intermediate voltage, it is a problem that the IGBT is not completely turned on.